The ULTIMATE GUIDE to Idle Tuning! (For ECU Upgrades & Engine Swaps)

This video can apply to all sorts of cars so share it with your friend who's got a sick swap that won't idle right! See below for more notes about this video.
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Extra Video Notes:

0) Yes, step zero. MAKE SURE you don't have any vacuum leaks before tuning idle.

1) PID values in the idle settings could have a video of their own, the coverage was very brief here. See tuning manuals for more information.

2) An alternative to unplugging the ISCV valve during idle screw setting is to lower idle to 0% duty in the tuning software.

3) In the MEITE idle settings there's something called "PID Deadband" that can be very useful. If you're using closed loop, and have issue with idle hunting but only by 50-100RPM, try increasing the Deadband to a larger value. This is the amount of error (Target RPM vs Actual RPM) that's allowed by the ECU where it will not attempt to chase the target. So if your target is 850RPM, and your engine is idling at 900RPM, with a Deadband setting of 50RPM, it will not attempt to chase it down to 850.

5) If you have a 1990-1993 (1.6L) Federal car, or 1990-1992 California car, it runs what's called batch fuel injection. This is where #1/3 and #2/4 fuel injectors fire simultaneously. You may notice, especially with larger injectors, that idle AFR needs to be in the 13's to be stable, this is normal. Alternatively, you can add 2 wires between your fuel rail and ECU to set up sequential injection. You need 1 signal wire per injector to do this (Early cars had 1 signal per 2 injectors.)

6) There is a lot that goes into this simple seeming topic. It can be harder even than cruise tuning or WOT tuning at times. If you guys have any pro tips you've learned from experience, drop them in the comments!
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Additional Info:
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0:00 Intro
0:51 Idle Components
6:27 Base Idle Setting (Stock & Standalone)
10:43 Open vs. Closed Loop Modes
16:30 What Variables Can Affect Idle?
18:59 What If The Car Won't Idle At All?
23:29 Idle Dipping / Stalling
26:26 Spark Scatter / Idle Advance
31:13 Pro Tip & Additional Idle Settings
34:29 Setting Up A/C & Fans
39:18 Outro

[knowsnothing]

A few tips: 1) Before you adjust the idle set screw mark your screwdriver with a marker and count the number of turns to fully close. Then write it down. That way you can always return it to stock

2) In Closed Loop Idle: Bracket your spark map in the idle area. That means set your low rpm to like 700, 900, 1250. I set mine to 14 degrees in the 700 & 900 and then advance it in the 1250 area to a point that keeps it from hunting/surge/ above this area. This will be used in conjunction with other functions below.

3) In closed loop idle set your Idle Cranking Duty/Steps to a Duty % high enough that you don’t need to depress the throttle pedal.

4) In Closed Loop Idle “Closed Loop Initial Values”. I bracket my setting like above starting at 700 rpm. Because I want my car to idle at 850 rpm, if it’s ever below 850 when it first goes into CLI it will ramp up to 850 by adding a higher Duty % at 700. Then as rpm increases on the scale drop the Duty % . This also seems to help steady it. My target rpm values are 700, 850, 950, 1100, 1200. I set the highest value of your IACV’s duty % in the 700 rpm field and taper it off the higher you go in the rpm scale.

5) Play with PWM Idle Voltage Compensation. I set my charging voltage, which is like 13.5 to 0.0 PWM. I put these numbers in the middle of the range. To the left on the scale, the voltage drops (due to load) all the way to 11.0 volts. As load increases the voltage drops and so want to add Duty % to the IAC to compensate. I use 2 % at 11 amps and -3.1 at 14.5 amps. This brackets your idle based off things like the load from lights, radio, AC etc.

6) Idle Load Advance. This can advance timing when load increases similar to above. At low load below 30% I have my advance set to 0. At the highest load setting of 70 my advance is set to 4 degrees. 0-4 degrees from 30-70 Load%

7) PID settings are not that helpful in MS2 but P & I are less effective than the D settings in my experience. I set my Gain to 3200 my P to 20.0, I to 60.0, and D to 200.

I don’t have PS or AC but I’m putting it back in. My idle is rock solid in CL at 850 rpm. Good luck everyone!

[mitchgoldfarb]

Iv been waiting 2 years for this video… my prayers have been answered. Thank you

[SpeedWhomp]

I literally just got my car with a new MS to crank over yesterday and was about to start watching idle tuning videos. Holy good timing Batman!

[sugoi]

please do acceleration enrichment tuning, its another huge deal with having an actual dailyable setup

[gm]

Imma call it now, pretty sure this is going to become one of Gregs most watched videos

[grahamnelson]

Glad to see daddy Greg calling out all the jabronis dropping into neutral at the end of every pull

[sn]

Dude, my name is Zach and that part where you said to pay attention really freaked me out lol. I'm too stoned for this. I should also mention I have a 1.6 and i have some idle issues

[CashedOutCars]

Less exciting than big boost but very helpful!

[FDB]

Greg: “Oh wow you actually clicked on this video”
Me: “What? You didn’t expect me to watch a new CarPassion video??

[matthewdrake]

FINALLLY MY GOD YOU ARE AMAZING CRAIG! Seriously so thankful to be a part of the miata community!

[evannoriega-thomas]

This is a video that so many people, including myself, needed. I switched to a standalone a couple months ago and even though my car doesn't run now, I am super excited to get it running so I can fine-tune some of these settings myself instead of going back and forth with my tuner.

[godsy]

All the comments and likes speak for themselves Greg. Really useful guide, thank you.

[EndriuGolara]

I don't have a miata, neither project car, but I probably will watch entire video because you always mention many interesting things

[OGPedXing]

Good tips, keep in mind if adding throttle keeps it running, you might have too much fuel rather than too little air. 👍

[andrewbutcher]

I have a ME211, got the tuner to work his magic and never touched it scared of messing it up this gives me way more confidence to play around with it. Cheers greg

[miokujou]

Getting this channel recommended to me is one of the best things YT ever did! Thanks YT!

I love vids like this that goes in depth with the explanation plus actually showing what will happen if do this and that. Cars now a days are an engineering marvel with more than a century of R&D put into them. Being able to explain these kind of things in a way that ordinary people like me can understand shows how good of a teacher you are. Great Job!

[warrendegonzague]

Thank you! You may not remember but I DM'd you about these things and you really set me in the right direction. Now, a video... nd you explain stuff really good. Thanks again big bro

[Everydayprojects]

My car idles perfectly at 10:1 and 12:1 lol but that’s because I raised my idle speed and increased my iac valve duty cycle, this is a great video

[liorlevi]

I must take a few minutes to write this comment. First of all, the video quality is of a high standard. The explanations you give can also be understood by people who do not really understand the subject. Secondly, you mentioned that the original ecu should be respected for all the little details that are controlled by it. And when I think about it it's crazy. There are so many things that need to happen and it is not so simple that it just works in every possible condition. It just makes me think how hard it is to calibrate a computer to an automatic transmission ... and one last thing is to thank you for sharing your extensive knowledge with us. I really appreciate it.

[TeddyD]

Engine idle is critical ! Thanks for doing this, I’m about to install MS on my 94